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Running Warm

Joined
Mar 20, 2006
Location
Cincinnati Ohio
My 90 240 is running warmer than usual. I can reduce the temperature to normal operating temperature by turning the heater on. The thermostat is about a year old.

Just seeing if there is anything to look out for. I'm putting in a new thermostat this week. The plugs look fine and car runs well. Has anyone had a radiator go bad internally? I don't see any leaks.
 
Have you ever replaced the water pump? How many miles on it? Are you sure it's overheating? How do you know? Does the cluster still have the temp faker board?Do this first, then check temperatures with an ir thermometer on the radiator hoses to see if it's a radiator issue and report back.
 
Have you ever replaced the water pump? How many miles on it? Are you sure it's overheating? How do you know? Does the cluster still have the temp faker board?Do this first, then check temperatures with an ir thermometer on the radiator hoses to see if it's a radiator issue and report back.

This. Also checking rad temp with an IR therm doesn?t work if it?s a shiny rad. So point it at block and thermostat housing. 180-200 is normal.

Have a fan shroud? Does it overheat at cruise or idle or what
 
Have you ever replaced the water pump? How many miles on it? Are you sure it's overheating? How do you know? Does the cluster still have the temp faker board?Do this first, then check temperatures with an ir thermometer on the radiator hoses to see if it's a radiator issue and report back.

I replaced the Water pump with the new motor. Motor probably has 3000 miles on it. I'm not 100 certain it's overheating. The gauge never goes past the middle dot unless it's about to overheat. Original 90 cluster. Worked fine for 28 years. I'll have to fine my IR thermometer. The plugs look fine and all cylinders are 100+Psi compression. I have block tester coming. The radiator is from a 87 Volvo.
 
I replaced the Water pump with the new motor. Motor probably has 3000 miles on it. I'm not 100 certain it's overheating. The gauge never goes past the middle dot unless it's about to overheat. Original 90 cluster. Worked fine for 28 years. I'll have to fine my IR thermometer. The plugs look fine and all cylinders are 100+Psi compression. I have block tester coming. The radiator is from a 87 Volvo.

Yes to fan shroud and overheats when driving. Not at idle.

First, I would remove the temp faker following the instructions in the link I initially posted. Sounds like it could possibly be a failing temp faker board. Once that's done, check your radiator for hot spots using your IR thermometer. It could possibly be clogged radiator.
 
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The IR showed 180F on hoses and water pump. I got around 170 on top of radiator. I couldn't get a good reading on the middle of the radiator since there is too many things in the way. The car ran fine and the gauge was were it needs to be. The only thing I changed was the shroud was not hooked in at the bottom. It had a small gap away from the radiator at the bottom.
 
Has anyone had a radiator go bad internally?

When I had my radiator tanks removed for rodding after overheating while driving we found that the input tank was filled half way up with junk so that the lower part of the radiator tubes were not carrying any water at all. That plus the tubes desperately needed cleaning.

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I probably should have installed a new radiator but I wanted to retain the original copper one. It has worked well for 4 years now.

Every small town used to have a radiator shop but now I wish you well on finding a shop to work on in. With the arrival of aluminum cores and plastic tanks you can get a new one for about the same price as a rework.

Don't tell the EPA about the shop I found as a half dozen within a hundred miles of my home have closed in recent years.

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I doubt that small gap was your problem unless it’s warm out where you live and it only ‘overheats’ at idle. Driving without a shroud is never a good idea (even on a stock 240, but especially on a car with a FMIC or any other heat exchanger up front), but you can get away with it on the highway.

Sounds like a flaky board to me.

I would also measure temps at thermostat housing, head, and a freeze plug/casting plug. I’ve always found the casting plugs to give the most consistent and accurate readings. Intake side, obviously..
 
I replaced the Water pump with the new motor. Motor probably has 3000 miles on it. I'm not 100 certain it's overheating. The gauge never goes past the middle dot unless it's about to overheat. Original 90 cluster. Worked fine for 28 years. I'll have to fine my IR thermometer. The plugs look fine and all cylinders are 100+Psi compression. I have block tester coming. The radiator is from a 87 Volvo.

100+ compression? That seems really low. Are you sure the timing belt is installed correctly?
 
I doubt that small gap was your problem unless it?s warm out where you live and it only ?overheats? at idle. Driving without a shroud is never a good idea (even on a stock 240, but especially on a car with a FMIC or any other heat exchanger up front), but you can get away with it on the highway.

Sounds like a flaky board to me.

I would also measure temps at thermostat housing, head, and a freeze plug/casting plug. I?ve always found the casting plugs to give the most consistent and accurate readings. Intake side, obviously..

In Cincinnati the weather outside has been at both ends of the thermometer for the past month, but not warm enough to cause overheating. I vote mechanical issue rather than ambient temp issue.
 
Have you verified that the water pump belt isn't slipping?

The belts are really tight, I just replaced them. With the alternator issues I had I took care of that. I'll keep my eye on the temp. I just replaced my thermostat since it's cheep. I'll see how it goes. I may have another clutch for a fan to try out at my house if the symptoms come up again.
 
I did put oil in the cylinders and the compression didn't change during testing. The belt is lined up, I have an adjustable cam gear set at 0 and IPD turbo cam. Not sure if that would help reduce compression.
 
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